The human keratin fibres to which the invention applies are especially head hair, the eyebrows, the eyelashes, beard hairs, moustache hairs and pubic hairs. More especially, the invention applies to human head hair and/or eyelashes.
Hair growth and hair renewal are mainly determined by the activity of the hair follicles and of their matrix environment. Their activity is cyclical and comprises essentially three phases, namely the anagenic phase, the catagenic phase and the telogenic phase.
The anagenic phase (active phase or growth phase), which lasts several years and during which the hair gets longer, is followed by a very short and transient catagenic phase that lasts a few weeks. During this phase, the hair undergoes a change, the follicle becomes atrophied and its dermal implantation appears higher and higher.
The terminal phase or telogenic phase, which lasts a few months, corresponds to a resting phase of the follicle and the hair ends up falling out. At the end of this rest period, a new follicle is regenerated in situ and another cycle begins.
The head of hair is thus under permanent renewal, and, out of the approximately 150 000 hairs that make up a head of hair, about 10% are at rest and will be replaced within a few months.
The natural loss or falling-out of the hair may be estimated, on average, as being a few hundred hairs per day for a normal physiological state. This process of permanent physical renewal undergoes a natural change during ageing, the hairs become finer and their cycles shorter.
In addition, various causes may result in a substantial, temporary or permanent loss of hair. This may be loss and impairment of hair at the terminal stage of pregnancy (post-partum), during states of dietary malnutrition or imbalance, during physiological stress, or during states of asthenia or of hormonal dysfunction, as may be the case during or at the terminal stage of the menopause. It may also be a case of loss or impairment of the hair related to seasonal phenomena.
It may also be a matter of alopecia, which is essentially due to a disturbance in hair renewal, resulting, in a first stage, in acceleration of the frequency of the cycles to the detriment of the quality of the hair, and then of their quantity. The successive growth cycles result in hairs that are finer and finer and shorter and shorter, gradually transforming into an unpigmented down. Certain areas are preferentially affected, especially the temporal or frontal lobes in men, and a diffuse alopecia of the crown of the head is observed in women.
The term alopecia also covers a whole family of afflictions of hair follicles whose final consequence is the permanent, partial or general loss of the hair. This is more particularly a matter of androgenic alopecia. In a large number of cases, early loss of hair occurs in genetically predisposed individuals; this is then a matter of andro-chrono-genetic alopecia. This form of alopecia especially affects men.
In certain dermatoses of the scalp with an inflammatory component, for instance psoriasis or seborrhoeic dermatitis, hair loss may be greatly accentuated or may result in highly disrupted follicular cycles.
The colour of human hair and skin depends on various factors and especially on the seasons of the year, race, sex and age. It is mainly determined by the concentration of melanin produced by the melanocytes. These melanocytes are specialized cells that synthesize melanin via particular organelles, the melanosomes.
Melanin synthesis (or melanogenesis) is complex and schematically involves the following main steps:
Tyrosine - - - >Dopa - - - >Dopaquinone - - - >Dopachrome - - - >Melanin
Tyrosinase (monophenol dihydroxyl phenylalanine: oxygen oxidoreductase EC 1.14.18.1) participates in this sequence of reactions by especially catalysing the reaction for conversion of tyrosine into dopa (dihydroxyphenylalanine) and the reaction for conversion of dopa into dopaquinone.
The upper part of the hair follicle appears as a tubular invagination of the epidermis, which is buried just down to the deep layers of the dermis. The lower part, or hair bulb, itself comprises an invagination in which is found the dermal papilla. Around the dermal papilla, in the lower part of the bulb, is an area populated with cells with a high degree of proliferation (matrix cells). These cells are the precursors of the keratinized cells that will constitute the hair. The cells that result from the proliferation of these precursors migrate vertically in the bulb and become gradually keratinized in the upper part of the bulb; this assembly of keratinized cells will form the hair stem. Pigmentation of the hair and of other bodily hairs requires the presence of melanocytes in the bulb of the hair follicle. These melanocytes are in an active state, i.e. they synthesize melanins (or melanin pigments). These pigments are transferred to the keratinocytes intended to form the hair stem, which will give rise to the growth of a pigmented head hair or other bodily hair. This structure is known as a “follicular pigmentation unit”.
It is known that, in the majority of populations, a brown skin coloration and maintenance of a constant coloration of head hair are important aspirations.
It is accepted that the appearance of grey or white bodily hairs and/or head hairs, or canities, is associated with a decrease in melanin in the hair stem. This phenomenon occurs naturally during the life of an individual. However, people are seeking to have a more youthful appearance and, with an aesthetic aim, they are often tempted to combat this phenomenon, especially when it occurs at a relatively early age.
One of the causes of hair loss, is oxidative stress induced especially by ultraviolet radiation. Although ultraviolet (UV) rays are known for transiently improving certain skin complaints, numerous literature data establish their role in oxidative stress and their involvement in accelerating ageing of the skin (photoageing). Ultraviolet radiation generates in the skin reactive oxygen species that damage cells by affecting the molecular and enzymatic antioxidant systems.
The skin, the scalp and the hair are the outermost organs of our body and are thus the first targets for environmental stress factors, most particularly represented by the ultraviolet radiation of sunlight, UVB and UVA.
Hair follicles are sensitive to the state of the extracellular matrix. Specifically, in the course of the successive hair cycles, the hair follicle is either in the upper part of the dermis (telogenic phase) or in the lower part of the dermis or hypodermis (anagenic phase). By way of example, perifollicular fibrosis participates in excessive hair loss in man (Yoo H. G. et al., 2006, Biol. Pharm. Bull., 29(6): 1246-1250).
Human hair follicles are also directly sensitive to oxidative stress: the studies described in the document by Arck et al., 2006, FASEB J., 20(9):1567-1569 demonstrate that oxidative stress impedes their growth and pigmentation.
Thus, the hair follicles directly or indirectly suffer the effects of oxidative stress. It thus appears important to seek to limit the formation of radical species in the skin and the scalp in order to limit excessive hair loss.
Novel active compounds are thus sought, which can induce or stimulate hair growth and/or reduce hair loss caused by oxidative stress induced especially by UV radiation.
Patent application WO 97/32562 discloses N-aryl-2-hydroxyalkylamides, patent application WO 98/05654 discloses 3-aryl-2,4-dioxooxazolidines, patent application EP 916 652 discloses N-aryl-2-hydroxyalkylamides and patent application WO 00/0 059 866 discloses benzoic acid ester derivatives, for stimulating or inducing hair growth and/or for stopping hair loss. These compounds pose stability or solubility problems in the supports of the compositions.
The Applicant has discovered a new family of compounds may especially be favourable towards stimulating and/or inducing the growth of keratin fibres, especially human keratin fibres, and/or towards halting their loss and/or increasing their density.
One subject of the present invention is the cosmetic use of at least one jasmonic acid derivative that will be defined in detail hereinbelow, and also an optical isomer thereof and/or a salt thereof, in a composition comprising a physiologically acceptable medium, for the purpose of inducing and/or stimulating growth of the keratin fibres, in particular human keratin fibres, and/or halting their loss and/or increasing their density.
Another subject of the present invention is a cosmetic process for the purpose of inducing and/or stimulating growth of the keratin fibres, in particular human keratin fibres, and/or halting their loss and/or increasing their density, consisting of applying a composition comprising in a physiologically acceptable medium, at least one jasmonic acid derivative that will be defined in detail hereinbelow, and also an optical isomer thereof and/or a salt thereof.
The term “skin” means any cutaneous surface of the human body, including skin, mucous membranes and semi-mucous membranes, thus including the lips, the scalp and also the skin's appendages, especially the nails, bodily hair and head hair.
According to the invention, a “physiologically acceptable medium” is either a medium that is cosmetically or pharmaceutically acceptable and compatible with the skin, mucous membranes, the nails and/or the hair, or a medium that can be administered orally.
The term “keratin fibres” means those of mammals of the animal species (for example dogs, horses or cats).
For the purposes of the invention, the term “human keratin fibres” means head hair, the eyebrows, the eyelashes, beard hair or moustache hair.
Other subjects of the invention will be defined later in the rest of the description.
The compounds according to the invention are represented by formula (I) below:

in which:
R1 represents a radical COOR3, R3 denoting a hydrogen atom or a C1-C4 alkyl radical, optionally substituted with one or more hydroxyl groups;
R2 represents a linear saturated or unsaturated hydrocarbon-based radical containing from 1 to 18 carbon atoms, or a branched or cyclic saturated or unsaturated hydrocarbon-based radical containing from 3 to 18 carbon atoms;
and also the optical isomers thereof, and corresponding salts thereof.
Preferably, R1 denotes a radical chosen from —COOH, —COOMe, —COO—CH2—CH3, —COO—CH2—CH(OH)—CH2OH, —COOCH2—CH2—CH2OH and —COOCH2—CH(OH)—CH3. Preferentially, R1 denotes a radical —COOH.
Preferentially, R2 denotes a saturated or unsaturated linear hydrocarbon-based radical, preferably containing from 2 to 6 carbon atoms. In particular, R3 may be a pentyl, pentenyl, hexyl or heptyl radical.
The salts of the compounds that may be used according to the invention are chosen in particular from the salts of alkali metals, for example sodium or potassium; the salts of alkaline-earth metals, for example calcium, magnesium or strontium, metal salts, for example of zinc, aluminium, manganese or copper; ammonium salts of formula NH4+; quaternary ammonium salts; salts of organic amines, for instance methyl-amine, dimethylamine, trimethylamine, triethylamine, ethylamine, 2-hydroxyethylamine, bis(2-hydroxyethyl)-amine or tris(2-hydroxyethyl)amine salts; lysine or arginine salts. Salts chosen from those of sodium, potassium, calcium, magnesium, strontium, copper, manganese and zinc are preferably used.
According to one embodiment, the compound of formula (I) is chosen from 3-hydroxy-2-[(2Z)-2-pentenyl]cyclopentaneacetic acid or 3-hydroxy-2-pentyl-cyclopentaneacetic acid or a corresponding salt thereof, and is preferably 3-hydroxy-2-pentylcyclo-pentaneacetic acid and especially the sodium salt of 3-hydroxy-2-pentylcyclopentaneacetic acid.
The compounds of formula (I) are known per se and have been described and synthesized in patent application EP 1 333 021.
Thus, the invention also relates to the cosmetic use of at least one jasmonic acid derivative of formula (I), and also an optical isomer thereof and/or a salt thereof, in a cosmetic composition for human hair care, for the purpose of treating alopecia of natural origin and in particular androgenic alopecia. Thus, this composition can maintain the hair in good condition and/or can combat natural hair loss, more especially in the case of men. This composition can thus maintain the hair in good condition and/or improve its condition and/or its appearance.
A subject of the present invention is a cosmetic process for inducing and/or stimulating growth of the human keratin fibres (especially the hair or the eyelashes) including the scalp and the eyelids characterized in that it consists in applying to the said keratin fibres a cosmetic composition comprising in a physiologically acceptable medium, at least one jasmonic acid derivative of formula (I), and also an optical isomer thereof and/or a salt thereof, in leaving it in contact with the keratin fibres and optionally in rinsing the said fibres and/or the said skin.
This treatment process does indeed have the characteristics of a cosmetic process in so far as it makes it possible to improve the aesthetic appearance of human keratin fibres and especially the hair and the eyelashes by giving them greater vigour and an improved appearance. In addition, it may be used daily for several months, without medical prescription.
A subject of the present invention is a cosmetic process for inducing and/or stimulating growth of the eyelashes and/or halting their loss and/or increasing their density, characterized in that it consists in applying on the eyelashes and/or eyelids a mascara composition comprising in a physiologically acceptable medium, at least one jasmonic acid derivative of formula (I), and also an optical isomer thereof and/or a salt thereof, in leaving it in contact with the on the eyelashes and/or eyelids. This mascara composition may be applied alone or as a base coat for a standard pigmented mascara and may be removed like a standard pigmented mascara.